Abstract : The Reduced Vertical Separation Minima (RVSM) experiment resulted from the conclusion reached by the North Atlantic System Planning Group to carry out studies aimed at achieving early implementation of RVSM in the North Atlantic (NAT) Region. RVSM is an approved International Civil Aviation Organization concept to reduce aircraft vertical separation from the Conventional Vertical Separation Minima (CVSM) of 2000 ft to 1000 ft, between flight levels 290 and 410, within a designated portion of the NAT Region. RVSM Phase II studies were conducted in September 1994 at the New York Air Route Traffic Control Center (ARTCC) Dynamic Simulation Laboratory. Phase II investigated workload effects and the feasibility of transitioning aircraft to and from CVSM altitudes and from and to RVSM altitudes within radar sectors R65 and R86 under various traffic conditions. The study was also aimed at determining whether RVSM should be employed exclusively in sector R65 or in both sectors R65 and R86. RVSM was instrumental in reducing controller workload when a majority of the traffic traveled eastbound. A decrease in workload was not observed while utilizing RVSM for westbound traffic. Post-mn discussions and questionnaires also revealed some concerns over the implementation of RVSM. Frequently reported concerns were: separating RVSM-equipped and non-RVSM-equipped aircraft, difficulty maintaining data block separation during RVSM, and the possibility of aircraft flying into CVSM airspace at an RVSM altitude due to a temporary lack of communication. Simulation results indicated that it is feasible to use domestic oceanic sectors R65 and R86 as RVSM transition airspace'.